Protein sorting Flashcards
Retrograde vs. Anterograde transport directions
Retrograde-> plasma membrane
- vesicle fuses with plasma membrane/ exocytosis
Anterograde-> nucleus
- cell balances flow of lipids towards PM caused by retrograde transport
Types of secretion (all _______)
Constitutive, Regulated, Polarized
all exocytosis
Constitutive secretion process
Vesicles bud from TGN, move directly to cell surface & fuse w/ plasma membrane
- unregulated: continuous and independent of external signals
Regulated secretion process
Secretory vesicles accumulate in cell & fuse with plasma membrane ONLY in response to specific signals
- EG: neurotransmitter release
Polarized secretion process
exocytosis of proteins is limited to specific surface of cell
- EG: intestinal cells secrete digestive enzymes only on the side of the cell that faces into the intestine
Phagocytosis
solid particles are ingested
Pinocytosis
liquids are taken up
Draw out receptor mediated endocytosis
(check in doc)
Process of exocytosis
(check in doc)
Coated vesicles (basic process)
Clathrin & adaptor proteins drive flat membrane into spherical vesicle, closing over materials outside of cell
Dynamin hydrolyzes GTP to tighten rings & separate vesicle from PM
Uncoating vesicles
Removal of clathrin coat, requires energy in form of ATPase
Triskelion
Basic unit of clathrin lattices that assemble into hexagons & pentagons to close the coat
COPI coated vesicles
Involved in retrograde transport from Golgi->ER
- coated with COPI & ARF– requires GTP energy
COPII coated vesicles
Involved in anterograde transport from ER->Golgi
- similar to ARF– using SarI
Importance of SNARE proteins
Proper sorting and targeting of vesicles relies on v-/t-SNARE proteins
Complementary molecules that allow recognition between vesicles & their targets
